Felt I had to comment on some of the stuff that being peddled on here.
Remember the AAIB gets involved only in crashes, and ask yourself how the over-use of a GPS can cause a crash.
Peter, you must have read some of the AAIB's bulletins to be such an expert on them, in which case you will have forgotten that the AAIB regularly investigates all manner of incidents, including crashes, as you put it, but also many other incidents as well where not a scratch is put on anything.
This is not a personal attack on you but I cringe at some of your comments as you obviously have no idea of some of the methods of the AAIB, or the expertise and skill of its investigators, all of whom (the pilot ones) are current and experienced pilots with varied backgrounds.
This following quote from a US aviation site is probably close to what they are getting at:
I was climbing out of XXX; had switched from XXX tower frequency to YYY ATC to pick up flight following. In the climb out phase; while in communication with YYY ATC; my GPS crashed. While recycling my GPS; I inadvertently wandered. I took a wide climb out under an unplanned sector class B airspace; which a ceiling of 4;000; instead of 5;000. Moments later; ATC informed me I was climbing into class B airspace. I made an immediate descent and turn to the left. My GPS rebooted and I continued my flight. The lesson learned is how important it is to be ready with back up navigation. Also; since ATC is there to help; I should have asked for vectors.
On the subject - task fixation leads to disorientation and this applies to GPS more than anything else.
I fly heavy metal for a living (and regularly enter LAT/LONGs!) but when I go up in the club aircraft it is with a half-mill chart and the Mk1, the GPS may be switched on but I don't use it for simple VFR flying - prefer looking out of the window. If anything, knowing the background of some of the AAIB guys, they will be commenting on incidents which highlight the lack of situational awareness of some who yet simultaneously know their lat/long to fraction of a minute of arc.